The Foreign Affairs Committee said that appointing Sir John Jenkins, the ambassador to Saudi Arabia, to lead the "secretive" review gave the perception a foreign state had "undue influence" over the report.

The Brotherhood played a leading role in Egypt's 2011 revolution and is considered a terrorist organisation by several countries – despite previously taking part in democratic elections on a peaceful platform.

Foreign Office

The committee said the FCO had "hindered" its inquiries by refusing to give it a full, or redacted copy of the review, or allow Sir John to give oral evidence.

There was a delay of 18 months between the review's completion and the release of its main findings last December on the last day the Commons sat before the Christmas recess.

There was speculation that the report was held back because Middle Eastern allies crucial in the fight against Isil would be displeased with the conclusion.

Supporters of the Muslim Brotherhood

The committee warned the handling of the review threw up wider concerns about the FCO's attitude to what constitutes "political Islam".

The committee report said: "Notwithstanding his knowledge, experience, and professional integrity, Sir John Jenkins's concurrent service as UK ambassador to Saudi Arabia made his appointment to lead the Muslim Brotherhood Review misguided.

"It created the impression that a foreign state, which was an interested party, had a private window into the conduct of a UK Government inquiry.

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"Whilst we have seen no evidence to suggest that Saudi Arabia was able to exercise undue influence over the report, the appointment of Sir John Jenkins created the perception that this was the case.

"This has undermined confidence in the impartiality of the FCO's work on such an important and contentious subject.

"This secretive review sought to understand the Muslim Brotherhood, but failed to mention some of the most significant factors influencing the Brotherhood - not least its removal from power in Egypt in 2013 and the subsequent repression of its supporters."